WEG drives · Fault guide
WEG CFW Drive Fault Codes: Meaning, Causes and When to Send for Repair
Common WEG CFW fault codes and what to do about themA WEG CFW drive fault code tells you which protection tripped, not which part failed. This guide lists the common codes, what usually causes them, what to check first, and the point at which the drive needs bench repair.
Important: Star Automations is a WEG service partner. It is also an independent multi-brand repair company and is not an OEM service centre. Work described on this page is carried out by Star Automations. WEG is a trademark of its owner. Star Automations does not give warranty terms on this page; scope and conditions are confirmed for each job.
Common fault codes
| Code | Name | Usual causes | First safe checks |
|---|---|---|---|
| F021 | DC link undervoltage | Low or unstable input supply, failed pre-charge circuit, undervoltage setting above supply | Check supply voltage and phases; repeated trips with good supply point to the pre-charge or DC bus |
| F022 | DC link overvoltage | Regeneration from the load, deceleration ramp too short, supply too high | Lengthen the deceleration ramp; check braking resistor and supply |
| F071 | Output overcurrent | Excessive load, acceleration ramp too short, current limit set too high | Check mechanical load and ramps; disconnect the motor and see if the trip remains |
| F072 | Motor overload | Excessive shaft load, motor overload parameters set too low for the motor | Check load, motor current and the overload parameters |
| F074 | Ground fault | Short to earth on an output phase, motor cable capacitance on long cables | Check motor and cable insulation before any restart |
| F051 | IGBT overtemperature | Blocked heat sink, failed fan, high ambient, overload | Clean the heat sink, check the fan and ventilation |
| F078 | Motor overtemperature | Motor temperature sensor (PTC) trip from overload or poor cooling | Check motor cooling and the sensor wiring |
| F006 | Input voltage imbalance or phase loss | Missing phase, loose input connection, unbalanced supply | Check the input fuses, contactors and supply phases |
Fault numbering and wording can differ by drive series and firmware version. Always check the manual for your exact drive. WEG is a trademark of its owner.
When a fault keeps coming back
A fault that clears after a fix is a settings or load problem. A fault that returns with the motor disconnected, or at power-up, usually points to the drive itself: output switching devices, gate-drive circuits, pre-charge, DC bus capacitors or the control board. Repeated resets on a drive with a failing power stage can damage more parts, so stop and arrange an assessment.
- Overcurrent or ground fault with the motor disconnected
- Undervoltage or overvoltage trips with a healthy supply
- Blank display or no response at power-up
- Burnt smell, swollen capacitors or visible damage
What to send for an assessment
What to send: photo of the nameplate or rating label, full model code and serial number, the fault or alarm code on the display, what happened before the failure, your location and how urgent it is.
See our WEG CFW drive repair page.
Frequently asked questions
What does fault F021 mean on a WEG CFW drive?
F021 is DC link undervoltage: the DC bus fell below its minimum. Common causes are low or unstable supply voltage, a failed pre-charge circuit or an undervoltage parameter set above the supply. Check the supply first. If it repeats with a healthy supply, the drive needs assessment.
What does fault F071 mean on a WEG CFW drive?
F071 is output overcurrent. It is commonly caused by excessive load, an acceleration ramp that is too short or a current limit set too high. Disconnect the motor and see if the trip remains; if it does, the drive output stage may be at fault.
What does fault F074 ground fault mean?
F074 indicates a short to earth on one or more output phases, or high motor cable capacitance causing current peaks. Check motor and cable insulation before restarting. Restarting repeatedly into a ground fault can damage the output stage.
Should I keep resetting a drive that trips?
No. If a trip clears once after you fix the cause, that is normal. If it repeats with the motor disconnected or at power-up, stop resetting and arrange an assessment, because repeated resets can damage the power stage further.
Send your unit or project details
Tell us the product, model code, fault and location. We reply on WhatsApp or by email to agree the next step. WhatsApp: +91 97866 22233. Website: www.starautomations.com.
Message received
Our team replies by email or WhatsApp. For urgent requests, WhatsApp +91 97866 22233.
Star Automations is a WEG service partner. It is also an independent multi-brand repair company and is not an OEM service centre.